What Is EN ISO 16321? Safety Glasses Certification Explained
Written by Fraser — Trade Shades founder, electrician by day.
Every pair of proper safety glasses has a code stamped somewhere on the frame or lens. On ours it's EN ISO 16321-1. Most lads never ask what it actually means — they just trust it's there for a reason. Fair enough. Here's the reason.
What the standard actually tests
EN ISO 16321-1 is the current European standard for eye and face protection. It replaced the older EN166 standard, and it covers the same ground: impact resistance, optical clarity, and how the glasses hold up under real conditions, not just in a lab on a shelf.
To carry the mark, a pair has to survive a ball-drop or high-velocity impact test without the lens shattering into your eye. It has to meet a minimum standard of optical quality, so what you're seeing through the lens isn't distorted enough to be a hazard itself. And it has to be permanently and legibly marked — the standard itself insists on that, because a certification nobody can check isn't worth much.
That's the difference between a certified pair and something that just looks like safety glasses. A pair of sunglasses with a wraparound frame might look the part on a shelf. It hasn't been tested to take a flying chip of masonry or a snapped cable end. EN ISO 16321-1 has.
Why this matters more than people think
One flying chip. One split second. That's genuinely all it takes — a grinder throwing sparks, a chase releasing grit at speed, a cable whipping back. Most days nothing happens. The certification is what's between you and the day something does.
It's also what should be on the paperwork if you're ever asked to show what PPE you were issued and whether it was fit for purpose. Cheap uncertified glasses off a market stall don't have an answer to that question. Certified ones do.
Certified doesn't have to mean ugly
This is where a lot of tradespeople get caught out. There's an assumption that "properly certified" and "comfortable, decent-looking" are opposites — that you have to pick one. That's a hangover from PPE built by people who've never worn it on a real job.
Every pair we build is EN ISO 16321-1 certified and built to actually be worn — anti-fog, anti-scratch, a fit that doesn't dig in, frames that don't scream "hi-vis cupboard." The certification isn't a trade-off against comfort. It's the baseline. Comfort is what gets it actually worn instead of left in the van.
"One flying chip. One split second. That's all it takes. These are EN ISO 16321-1 certified — the standard that means they've actually been tested to take the hit."
What to check before you buy any pair
- Is the standard marked on the frame or lens? If you can't find it, it isn't certified — full stop.
- Is it EN ISO 16321-1, or the older EN166? Either is a real standard, but 16321-1 is the current one.
- Does the listing actually say what's certified — lens, frame, or both? A vague "safety-style" listing with no standard named is a red flag.
If a pair passes those three checks and doesn't fog up by 10am, you've found a proper set. Everything else is picking your colour and lens tint.
If you're weighing up which pair to actually go for, we've broken down what to look for as an electrician specifically. And if anyone's told you PPE like this is optional on site, it isn't — here's what the regulations actually say.
Trade Shades. EN ISO 16321-1 certified safety glasses, built by a working electrician. 4.8★ on Trustpilot, 65+ reviews.